OTC Antihistamine May Reverse Vision Damage Caused by Multiple Sclerosis

Clemastine fumarate improves optic neuropathy

Clemastine fumarate, a common antihistamine used to treat symptoms of allergies and the common cold, partially reversed damage to the visual system in people with multiple sclerosis (MS) in a preliminary study presented at the American Academy of Neurology’s 68th annual meeting in Vancouver, Canada.

The study involved patients with MS and optic neuropathy. In MS, the immune system destroys myelin, the protective coating around the nerves, which leads to damage along the nerves, slowing signals to and from the brain. Optic nerve damage is a common consequence of the disease.

“This study is exciting because it is the first to demonstrate possible repair of that protective coating in people with chronic demyelination from MS,” said investigator Ari Green, MD, of the Multiple Sclerosis Center at the University of California, San Francisco. “This was done using a drug that was identified at UCSF only two-and-a-half years ago as an agent with the potential to help with brain repair.”

The five-month study involved 50 subjects with an average age of 40 years who had MS for an average of five years and had mild disability. They all had evidence of stable chronic optic neuropathy, meaning that they were not recovering from recent optic neuritis.

The subjects performed vision tests at the start and end of the study. For one test, called a visual-evoked potential, the time for the transmission of a signal from the retina to the visual cortex was recorded. To be included in the study, the subjects had to have a delay in transmission time beyond 118 milliseconds in at least one eye and had to have evidence that they had an adequate number of nerve fibers to reinsulate. An improvement in the delay in transmission was considered a biomarker of myelin repair.

During the first three months of the study, the subjects were given either the antihistamine clemastine fumarate or placebo. For the second two months, those initially given the drug received the placebo and vice versa.

During the study, delays were reduced by an average of slightly less than 2 milliseconds in each eye per patient among those who received the antihistamine.

“While the improvement in vision appears modest, this study is promising because it is the first time a drug has been shown to possibly reverse the damage done by MS,” Green said. “The findings are preliminary, but this study provides a framework for future MS repair studies and will hopefully herald discoveries that will enhance the brain’s innate capacity for repair.”

The study subjects reported a modest increase in fatigue while taking the drug.

Green cautioned that more research with larger numbers of people is needed before doctors can recommend clemastine fumarate for people with MS.

Source: American Academy of Neurology; April 12, 2016.